How meteorological conditions influence aerosol-cloud interactions under different pollution regimes

Abstract. Aerosol-cloud interactions (ACI) involve complex physical and dynamical mechanisms, in which meteorological conditions play a crucial role. To investigate how the meteorological conditions impact ACI under different pollution regimes (polluted and clean) for marine liquid-phase clouds, the simulations are conducted using the chemistry version of Weather Research and Forecasting Model coupled with spectral-bin cloud microphysics. Our results indicate that, aerosols prolong cloud lifetime in humid environments. In dry conditions, they shorten cloud lifetime under low-to-moderate lower tropospheric stability (LTS) but further suppress the negative effects of entrainment in high-LTS environments with weak entrainment, ultimately extending cloud lifetime. Aerosols generally suppress precipitation but can enhance it during some intense cloud processes by promoting cloud vertical development in low-level clouds and increasing droplet amount in high-level clouds. The coordinated variations of cloud properties with meteorological conditions and aerosols reveal the regulatory role of meteorological factors on ACI. Specifically, under the winter monsoon background, the qualitative influence of aerosols on cloud properties is modulated by variations in updrafts and cold advection (characterized by LTS) driven by atmospheric circulation that co-varies with aerosol concentrations. Meanwhile, changes in atmospheric moisture govern the quantitative effects of aerosols on cloud development.